Tigers at the Phoenix Zoo are getting frozen fish snacks. Temporary cooling stations are popping up to welcome the homeless and elderly. And airlines are monitoring the soaring temperatures to make sure it's safe to fly as the western US falls into the grip of a dangerous heat wave.

A strong high-pressure system settling over the region today and through the weekend will bring extreme temperatures to the already blazing Southwest. Notoriously hot Death Valley in California is forecast to reach 129 degrees (54 Celsius), not far off the world-record high of degrees (57 Celsius) logged there exactly one century ago.

The National Weather Service predicts Phoenix could reach a high of 118 degrees (48 Celsius) today, while Las Vegas could see the same temperature over the weekend.

Temperatures are expected to soar across Utah and into parts of Wyoming and Idaho, where forecasters are calling for triple-digit heat in the Boise area through the weekend.

Cities in Washington state better known for cool, rainy weather should break the 90s early next week, while northern Utah - marketed as having "the greatest snow on Earth" - is expected to hit triple digits. In Albuquerque, New Mexico., the mercury hit 105 degrees (41 Celsius) on Thursday afternoon, the hottest it has been in the state's most populous city in 19 years.

"This is the hottest time of the year but the temperatures that we'll be looking at for Friday through Sunday, they'll be toward the top. We'll be at or above record levels in the Phoenix area and throughout a lot of the southwestern United States," said National Weather Service meteorologist Mark O'Malley. "It's going to be baking hot across much of the entire West."

Scientists say that the jet stream, the river of air that dictates weather patterns, has been more erratic in the past few years. It's responsible for weather systems getting stuck, like the current heat wave. Scientists disagree on whether global warming is the cause of the jet stream's behavior.

Even airlines are watching the mercury for any signs that temperatures could deter operations.